1. Field of the Invention
The present invention relates to a method for eliminating temperature-induced band switching in a ultra-wide band (UWB) voltage controlled oscillator (VCO).
2. Discussion of the Related Art
A phase-locked loop (PLL) is a common component in a communication system. In a typical PLL, a voltage-controlled oscillator (VCO) provides a signal which frequency varies according to a control signal applied at the VCO's input terminal. Conventionally, for a wideband VCO, spurs are reduced by dividing the entire frequency range into smaller bands. This approach can lead to problems. For example, as a result of such frequency divisions, only narrow frequencies are covered within each band. When the temperature changes, band-switching may be necessary for the PLL to remain tuned to the same frequency. In a video receiver, band-switching in the PLL may induce significant flickering in the received signal. In the prior art, spurs are reduced by decreasing the tuning sensitivity KVCO of the VCO However, decreasing KVCO also tends to result in band switching-induced screen flickering.